US4814607A - Method and apparatus for image recording of an object - Google Patents

Method and apparatus for image recording of an object Download PDF

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Publication number
US4814607A
US4814607A US07/042,478 US4247887A US4814607A US 4814607 A US4814607 A US 4814607A US 4247887 A US4247887 A US 4247887A US 4814607 A US4814607 A US 4814607A
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United States
Prior art keywords
flight
image
line
flying body
viewing angle
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US07/042,478
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English (en)
Inventor
Otto Hofmann
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LFK Lenkflugkoerpersysteme GmbH
Airbus Defence and Space GmbH
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Messerschmitt Bolkow Blohm AG
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Assigned to MESSERSCHMITT-BOLKOW-BLOHM GMBH reassignment MESSERSCHMITT-BOLKOW-BLOHM GMBH ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HOFMANN, OTTO
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B15/00—Special procedures for taking photographs; Apparatus therefor
    • G03B15/006—Apparatus mounted on flying objects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C11/00—Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
    • G01C11/02—Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
    • G01C11/025—Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures by scanning the object

Definitions

  • the invention is directed to a method and an apparatus for image recording of an object from a flying object by optically scanning the object.
  • a flying object for instance an earth satellite, flies at high altitude over the object, for instance the earth surface, and flies essentially parallel to the surface of the earth.
  • the object is then optically scanned in lines oriented essentially transverse to the direction of flight at a specific angle of view ⁇ , which lies in a vertical plane through the direction of flight.
  • the recorded image lines are subsequently processed into an overall image.
  • the resolution of the image recorded transverse to the direction of flight depends, among other things, on the focal length of the scanner used. Therefore, by increasing the focal length, the ground pixel can theoretically be made as small as desired, even at great flight altitudes, as they occur in the course of imaging the surface of the earth by satellites.
  • the pixel resolution in direction of flight is also dependent on the flight speed and the exposure time. In the case of satellites, the speed of flight is a predetermined, substantially invariable magnitude of approximately 7000 meters-per-second.
  • the exposure time for one line must thus be sufficiently small, or, accordingly, the line frequency must be sufficiently large.
  • the limited sensitivity of the sensors used hinders very short exposure times, resulting in the signal-to-noise relationship becoming unfavorable. The same considerations apply also for rapidly moving flying objects in ground proximity, if one requires a large resolution.
  • TDI sensors For map making imaging of the surface of the earth from cosmic space, a high ground pixel resolution and thus small ground pixel diameters are desired.
  • TDI sensors where TDI stands for "time delay and integration" have been developed. These sensors consist of several sensors lines arranged in parallel fashion, whose weak image signals are integrated from line to line. These sensors are, however, very expensive. Apart from that, the sensor lines must be very accurately aligned with the direction of flight, and the timing frequency of the line sensors must be exactly tuned to the image movement, i.e. to the speed of flight and the flight altitude of the flying object. Additionally, the sensitivity of the TDI sensor increases not proportionally with the number of the parallel lines, but rather only approximately proportionate to the root, since the noise also increases with the root.
  • An object of the invention is to provide a method and a device of the type which increases, in a simple manner, the resolution of the object pixels of the object in the direction of flight and flexibly adapts the resolution transverse to the direction of flight and match it with the direction of flight.
  • This object is achieved in a method for recording an image of an object from a flying body which flies over the object, the method comprising optically scanning the object at a specific viewing angle with respect to a direction of flight, in lines lying essentially transverse to the direction of flight, and combining the scanned image lines to form an overall image, characterized in that said method further comprises increasing the viewing angle with respect to the direction of flight during said scanning.
  • an apparatus for recording an image of an object from a flying body which flies over the object comprising a line scanner which optically scans a line on a surface of the object lying substantially transverse to a direction of flight of the flying body at a viewing angle with respect to the flight direction, and means for combining the image lines into an overall image, characterized in that said apparatus further comprises means for increasing the viewing angle ⁇ with respect to the flight direction.
  • the viewing angle ⁇ is increased with respect to the direction of flight during the scanning process, so that during a specific time interval of the image recording, the area scanned by one sensor line in the direction of flight has a smaller length than the projection of the flight path upon the object in the horizontal direction.
  • the viewing angle ⁇ is adjusted in a cyclical motion approximately proportional to the flight speed, beginning with an initial value which is then increased across a limited angular range and subsequently, for a short time, is again adjusted to the initial value.
  • a corresponding strip of the object is then recorded.
  • the strips can follow each other contiguously, if the object is simultaneously scanned at different viewing angles with several sensors, which are all regulated, in the sense of the invention, with respect to the flight direction.
  • the regulation's velocity can be tuned in such a manner that, viewed in the direction of flight, the length during one cycle of scanned area upon the surface of the object corresponds to the horizontal projection of the flight path during the cycle.
  • the viewing angle there exist several possibilities, for instance, swivelling the earth satellite around its pitching axis, displacing the objective relative to the image plane, which contains the sensor lines, as against the direction of flight, or displacing the sensor lines in the image plane in the direction of flight, or optical deviation means of another type can be provided. If several line sensors are provided, a special lens can be provided for each line sensor, or for a specific group of line sensors, so that the twisting of the viewing angle can be individually regulated.
  • the most favorable possibility is, however, to utilize several optoelectronic line sensors arranged transverse to the flight direction, and to position these line sensors in a carrier located in the image plane of the line scanner and to displace these sensors slowly with a cyclically functioning drive in the image plane during the scanning process and to return the same subsequently rapidly into the initial position.
  • the displacement velocity is chosen with respect to the flight speed of the flying object, the focal length of the line scanner, the number of the sensor lines and the flight altitude in such a way that the object is recorded without gaps.
  • FIG. 1 is a schematic view of an earth satellite for image recording of the earth surface with a line scanning method according to the invention
  • FIG. 2 is a schematic diagram of the method according to the invention.
  • FIG. 3 is an arrangement of line sensors in a line scanner according to the invention.
  • FIG. 1 shows schematically a portion 1 of the earth's surface, above which an earth satellite 2 flies in the direction of the arrow shown with the velocity v at a constant flight alititude H.
  • the projection of the flight path of the satellite 2 on the earth surface 1 in the horizontal direction is designated with 3.
  • An apparatus for image recording of the surface 1 is provided aboard the satellite 2, which contains, as an essential part, a line scanner 4 schematically indicated in FIG. 2.
  • This line scanner 4 includes an input optical arrangement 5 with a focal length c and several line sensors, in this case three line sensors 6a, 6b and 6c, in the image plane of the input optical arrangement. These line sensors 6a-6c are oriented transverse to the flight direction of the satellite 2 and are arranged on a carrier 7 according to FIG. 3.
  • the carrier 7 is conducted, similar to a conveyor belt, around two conveying rollers 8a and 8b, whereby one of the rollers 8a is driven by a motor 9.
  • the motion of the carrier 7 lies in the flight direction.
  • the spacing between the individual line sensors 6a-6c in this direction is designated with a.
  • the line sensors 6a, 6b or 6c image, respectively, lines 10a, 10b or 10c on the earth surface 1, so that in the course of the flight of the earth satellite 2, a surface strip 11 with the width of the line 10 is recorded by the line scanner 4.
  • the fan-shaped flat beam bundles, which constitute each line 10a, 10b or 10c, together with the assigned line sensor 6a, 6b, 6c, are designated with 12a, 12b and 12c, respectively.
  • the line sensors 6a-6c are, to begin with, oriented in such a manner that the viewing angle of the line sensor 6c is 90°, i.e. the radiation beam 12c lies in the vertical plane.
  • the beam 12a is directed forward, so that the viewing angle of the line sensor 6a is smaller than 90°.
  • the carrier 7 of the line sensors 6a-6c is displaced in the flight direction with a small constant displacement velocity vs during the flight of the satellite 2. This displacement velocity vs is maintained until, after a defined flight travel distance F of the satellite 2, the viewing angle of the sensor 6a lies in the vertical direction.
  • the beams associated with the line sensors 6a-6c after the flight travel distance F are shown in dotted lines in FIG. 2.
  • the line sensor 6a has recorded the partial strip A1, the line sensor 6b, the partial strip A2, and the line sensor 6c, the partial strip A3.
  • the equally wide partial strips are contiguous.
  • a pixel size D on the earth surface 1 in the flight direction can be calculated to be:
  • the resolution has thus been increased by a factor of 3 compared to a line scanner with one single line sensor.
  • Such an increased resolution capacity corresponds to that of a TDI sensor within approximately nine lines.
  • the motor 9 is reversed and returns the carrier 7, at high speed V r , to its original position. This is depicted in the right half of FIG. 2 in dotted broken lines.
  • the minimum distance a between the line sensors depends on the space requirements. The maximum distance is limited by the field of view of the lens 5 of the line scanner 4.
  • the displacement velocity and the duration of the cycle of the motor 9 depends on the number of the line sensors n, and thus, indirectly, also on the selection of this distance a.
  • the displacement velocity of the carrier 7 must be measured accurately and registered synchronously with the image line recording, so that the image coordinates of the line sensors are accurately known at each point in time of the line scanning.
  • the earth curvature has been neglected in each of the respective formulae given above. If the satellite flies at an altitude of 300 km., then the earth curvature measured with respect to the middle tangent with a flight path of 400 km. amounts to approximately 3.5 km., thus approximately 1% of the flight altitude. It is naturally possible to correct for this if the earth curvature has to be taken into account.
  • the invention can also be advantageously utilized in digital photomapping systems, in which three line sensor groups are used, which scan the earth's surface in respectively different viewing angles according to the method of the invention.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Facsimile Scanning Arrangements (AREA)
  • Stereoscopic And Panoramic Photography (AREA)
US07/042,478 1986-04-26 1987-04-24 Method and apparatus for image recording of an object Expired - Lifetime US4814607A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863614159 DE3614159A1 (de) 1986-04-26 1986-04-26 Verfahren und vorrichtung zur bildaufnahme eines objektes in zeilen
DE3614159 1986-04-26

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US4814607A true US4814607A (en) 1989-03-21

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US07/042,478 Expired - Lifetime US4814607A (en) 1986-04-26 1987-04-24 Method and apparatus for image recording of an object

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US (1) US4814607A (de)
DE (1) DE3614159A1 (de)
FR (1) FR2597985B1 (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5296926A (en) * 1991-11-19 1994-03-22 Nec Corporation Image data transmission system capable of obtaining a high resolution stereo image with reduced transmission data
FR2729479A1 (fr) * 1995-01-12 1996-07-19 Deutsche Forsch Luft Raumfahrt Compensation de l'effet de flou d'image
US5712678A (en) * 1988-12-08 1998-01-27 Messerschmitt Bolkow Blohm Gmbh Method and apparatus for scanning a terrain surface
US5883584A (en) * 1992-05-21 1999-03-16 Dornier Gmbh Earth observation method
WO2002018874A1 (en) * 2000-08-28 2002-03-07 Marine Research Wa Pty Ltd Real or near real time earth imaging system
US6462769B1 (en) 1998-12-07 2002-10-08 Universal City Studios, Inc. Image correction method to compensate for point of view image distortion
WO2003040653A1 (en) * 2001-11-09 2003-05-15 Marine Research Wa Pty Ltd Improved real or near real time earth imaging system and method for providing imaging information
US20080196578A1 (en) * 2002-12-19 2008-08-21 Eden Benjamin Z Personal Rifle-Launched Reconnaisance System
US8699867B2 (en) * 2010-09-30 2014-04-15 Trimble Germany Gmbh Aerial digital camera and method of controlling the same
US20150334325A1 (en) * 2012-12-28 2015-11-19 Datalogic Ip Tech S.R.L. Method and apparatus for acquiring images on moving surfaces
WO2019055122A1 (en) * 2017-09-18 2019-03-21 Raytheon Company DELAY ADJUSTMENT FOR SATELLITE IMAGE DIVERSITY

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4031465A1 (de) * 1990-10-05 1992-04-09 Johannes Schier Fernsteuerbare vorrichtung zur aufnahme von informationen im luftraum
FR3107953B1 (fr) 2020-03-03 2022-03-11 Airbus Defence & Space Sas Procédé d’acquisition d’images d’une zone terrestre par un engin spatial

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4543603A (en) * 1982-11-30 1985-09-24 Societe Nationale Industrielle Et Aerospatiale Reconnaissance system comprising an air-borne vehicle rotating about its longitudinal axis
US4628354A (en) * 1984-03-15 1986-12-09 Nec Corporation Image data transmission system capable of reproducing a high resolution image by the use of a simple structure
US4630111A (en) * 1983-11-04 1986-12-16 Ferranti Plc Image distortion correction system for electro-optic sensors
US4689748A (en) * 1979-10-09 1987-08-25 Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung Device for aircraft and spacecraft for producing a digital terrain representation
US4710809A (en) * 1985-06-29 1987-12-01 Deutsche Forschungs-Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. Method for the representation of video images or scenes, in particular aerial images transmitted at reduced frame rate

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2967211A (en) * 1952-11-13 1961-01-03 Servo Corp Of America Optical scanning mechanism
GB1375158A (de) * 1969-11-19 1974-11-27 Hawker Siddeley Dynamics Ltd
CH579265A5 (en) * 1974-08-12 1976-08-31 Klaey Hans Avoiding blurring of picture caused by moving camera - tiltable mirror arranged in front of lens compensates for angle changes
DE3434794A1 (de) * 1984-09-21 1986-04-03 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Optisches system zur bewegungskompensation von zeilen-scannern

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4689748A (en) * 1979-10-09 1987-08-25 Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung Device for aircraft and spacecraft for producing a digital terrain representation
US4543603A (en) * 1982-11-30 1985-09-24 Societe Nationale Industrielle Et Aerospatiale Reconnaissance system comprising an air-borne vehicle rotating about its longitudinal axis
US4630111A (en) * 1983-11-04 1986-12-16 Ferranti Plc Image distortion correction system for electro-optic sensors
US4628354A (en) * 1984-03-15 1986-12-09 Nec Corporation Image data transmission system capable of reproducing a high resolution image by the use of a simple structure
US4710809A (en) * 1985-06-29 1987-12-01 Deutsche Forschungs-Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. Method for the representation of video images or scenes, in particular aerial images transmitted at reduced frame rate

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5712678A (en) * 1988-12-08 1998-01-27 Messerschmitt Bolkow Blohm Gmbh Method and apparatus for scanning a terrain surface
US5296926A (en) * 1991-11-19 1994-03-22 Nec Corporation Image data transmission system capable of obtaining a high resolution stereo image with reduced transmission data
US5883584A (en) * 1992-05-21 1999-03-16 Dornier Gmbh Earth observation method
FR2729479A1 (fr) * 1995-01-12 1996-07-19 Deutsche Forsch Luft Raumfahrt Compensation de l'effet de flou d'image
US6462769B1 (en) 1998-12-07 2002-10-08 Universal City Studios, Inc. Image correction method to compensate for point of view image distortion
WO2002018874A1 (en) * 2000-08-28 2002-03-07 Marine Research Wa Pty Ltd Real or near real time earth imaging system
WO2003040653A1 (en) * 2001-11-09 2003-05-15 Marine Research Wa Pty Ltd Improved real or near real time earth imaging system and method for providing imaging information
US20080196578A1 (en) * 2002-12-19 2008-08-21 Eden Benjamin Z Personal Rifle-Launched Reconnaisance System
US7679037B2 (en) 2002-12-19 2010-03-16 Rafael-Armament Development Authority Ltd. Personal rifle-launched reconnaisance system
US8699867B2 (en) * 2010-09-30 2014-04-15 Trimble Germany Gmbh Aerial digital camera and method of controlling the same
US20150334325A1 (en) * 2012-12-28 2015-11-19 Datalogic Ip Tech S.R.L. Method and apparatus for acquiring images on moving surfaces
US10225502B2 (en) * 2012-12-28 2019-03-05 Datalogic Ip Tech S.R.L. Method and apparatus for acquiring images on moving surfaces
WO2019055122A1 (en) * 2017-09-18 2019-03-21 Raytheon Company DELAY ADJUSTMENT FOR SATELLITE IMAGE DIVERSITY
US10392136B2 (en) * 2017-09-18 2019-08-27 Raytheon Company Offload adjustment for satellite image diversity
AU2018334389B2 (en) * 2017-09-18 2022-11-10 Raytheon Company Offload adjustment for satellite image diversity

Also Published As

Publication number Publication date
FR2597985B1 (fr) 1992-09-25
FR2597985A1 (fr) 1987-10-30
DE3614159C2 (de) 1989-03-23
DE3614159A1 (de) 1988-02-04

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